Approximately ten percent of all human beings can be designated allergic or atopic. They have become sufficiently hypersensitive to substances commonly present in the environment to experience significant symptoms on exposure to these substances. The majority suffer from readily identifiable allergic symptoms such as hayfever, asthma, eczema, hives and localized swellings. Regardless of symptoms the preferred methods of therapy are either to remove the patient from the substance to which he is sensitive or failing that, to treat the patient with increasing doses of the substance and thereby elevate his threshold for reaction. The allergic symptoms are induced by the presence of allergens in the substances to which the individuals are sensitive. An allergen may be defined by first defining an antigen which is a substance that can stimulate the production of antibody in an animal, the produced antibody is specifically reactive with the antigen. An allergen is a special antigen which stimulates a synthesis of a class of antibody which causes allergy. Before either of the methods of therapy noted above can be applied it is necessary to identify the allergen. Currently, allergic hypersensitivity is determined by direct skin tests on patients. In the skin tests minute quantities of various allergens are injected into or under the skin, visible but usually readily tolerated lesions will appear on the skin of the patient at the point of injection of an allergen to which the patient is hypersensitive. The skin test has limitations. It does not work well in either the very young or the very old, there is some risk to the patient during skin testing and there are relatively few physicians expert in performing and interpreting skin tests so that the method cannot be made widely available and the method is a costly one. An in vitro system for assaying allergic hypersensitivity would be simpler, safer and cheaper than the skin test method. Such a system has not heretofore been available.